Do FC Porto sell out?

Excuse me, could you please elaborate on the statement "Do FC Porto sell out?" Are you referring to the selling out of tickets for their matches, merchandise, or perhaps a different aspect of the club's operations? I'm curious to understand the context in which this question is being asked. If it's about ticket sales, does FC Porto regularly see their stadium filled to capacity for home games, or are there factors that influence attendance levels? Additionally, how does the club's popularity and performance on the pitch factor into their ability to sell out events?